Horizontal Composter Handles Mortalities

Jun 15, 2007 12:00 PM, By Dale Miller Editor

The medium-sized Biovator was tested for compliance with Canadian regulations at a 1,250-sow farrow-to-finish unit.

Handling the inevitable mortalities on any hog farm creates both a practical and a biosecurity challenge. In some herds and regions, the problem has been exacerbated by higher-than-normal mortalities caused by porcine circovirus associated disease (PCVAD).

Canada's third-largest pork producer, The Puratone Corp. of Niverville, Manitoba met those challenges by developing a horizontal, in-vessel composter known as the Biovator. The company wanted an alternative to traditional composting, incineration or commercial rendering and, more importantly, to comply with Canadian federal regulations administered by the Ministry of Agriculture.

Tested in Quebec

Puratone set up a test project at a 1,250-sow, farrow-to-finish site utilizing a medium-sized Biovator (30 ft. long and 4 ft. in diameter).

The mortality composter is basically a long, rotating stainless steel cylinder that turns mortalities and a carbon source, such as wood shavings, into harmless compost. Smaller, 18-ft. versions and larger, 42 ft. versions are also available.

The insulated cylinder has three openings. The first set of doors is for loading mortalities, wood shavings and recycled compost. The second set of doors allows operators to measure temperatures and compost mass. At the end is the effluent door, which spills into a recuperation basin for long-term storage.

The objective of the Quebec project was five-fold:

To develop the compost recipes and mortality-carbon source mixing ratios;
To establish optimum operating temperatures, moisture levels and drum rotation frequencies and speeds;
To validate effectiveness in summer and winter periods;
To monitor specific bacteria and pathogen levels in the end product, and
To comply with Quebec law and regulation for the disposal of swine mortalities.

Dead animals were added to the load cell with a tractor front-end loader, five days a week. Weekend mortalities were added on Mondays. Animal weights were verified. Wood shavings, serving as the carbon source, were added to cover mortalities with 6-8 in. (150-200 mm) of material. Therefore, the ratio was 2.2 lb. (1 kg) of mortality to 1.5 lb. (0.7 kg) of dry wood shavings. No water was added.

Compost bones collected at the end of the cylinder were recycled with mortalities and new wood shavings at a rate of 2.2 lb. of mortality to 0.55 lb. new wood shavings and 0.97 lb. of the recycled matter.

The goal was to reach temperature above 100.4° F (38° C)to initiate the composting process. In cool/cold weather (below freezing), a 60,000 Btu/hour heater was necessary to achieve the desired temperatures on start up.

Temperatures and humidity levels were obtained five days a week and agronomic and pathogenic samples were collected every 14 days for specific periods.